首页|Revealing the vertical structure of in-situ fabricated perovskite nanocrystals films toward efficient pure red light-emitting diodes
Revealing the vertical structure of in-situ fabricated perovskite nanocrystals films toward efficient pure red light-emitting diodes
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The development of efficient perovskite light-emitting diodes(PeLEDs)relies strongly on the fabrication of per-ovskite films with rationally designed structures(grain size,composition,surface,etc.).Therefore,an understand-ing of structure-performance relationships is of vital importance for developing high-performance perovskite de-vices,particularly for devices with in-situ fabricated perovskite nanocrystal films.In this study,we reveal the vertical structure of an in-situ fabricated quasi-two-dimensional perovskite film.By combining time-of-flight sec-ondary ion mass spectrometry,energy dispersive spectroscopy,grazing incidence wide-angle X-ray scattering(GIWAXS),and low-temperature photoluminescence spectra,we illustrate that the resulting in-situ fabricated DPPA2Csn-1Pbn(Br0.3I0.7)3n+1(DPPA+:3,3-diphenylpropylammonium)film has a gradient structure with a very thin layer of ligands on the surface,predominantly small-n domains at the top,and predominantly large-n do-mains at the bottom owing to the solubility difference of the precursors.In addition,GIWAXS measurements show that the domain of n=2 on the top layer has an ordered in-plane alignment.Based on the understanding of the film structure,we developed an in-situ fabrication process with ligand exchange to achieve efficient pure red PeLEDs at 638 nm with an average external quantum efficiency(EQE)of 7.4％.The optimized device had a maximum luminance of 623 cd/m2 with a peak EQE of 9.7％.
MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices,School of Materials Science & Engineering,Beijing Institute of Technology,Beijing 100081,China
Experimental Center of Advanced Materials,School of Materials Science & Engineering,Beijing Institute of Technology,Beijing 100081,China
Shanghai Synchrotron Radiation Facility(SSRF),Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201204,China
Institute of Applied Physics and Materials Engineering,University of Macau,Macau 999078,China
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